Process for production of lubricating oil



/ lamz's, 1937.

an. MERRILL. ET Au. pnocass FOR morgucnou 01w LUBRICATING OIL Filed Oct. 24, 1952 Patented Dec; 1937 N D; TES mm TQOFFI CE f raocsss Fox raonocrron F LonmcA'rL M moon mm a. MerrllL LongBeach, and rump Subkow,

production of lubricating oil. it re late's toaprocessforthe production oi lubricating oil from petroleum by the use ofsol One of the distinctive characteristics ofa lu bricating oil is its viscosity; Itsgusefulnessas a lubricant depends, at leastin part uponits if 3 viscosity. For many purposes lubricants arede-t l0 sired whose viscosityfwill vary asqlittle ias postsible with jvariations in temperature, 1. e. have low temperature viscosity susceptibilities. Those fractions whicnexhibit 'a low temperature'visp cosity susceptibility are ofttimes'ireferred to as F5 the paraiiinic oils whereas the fractions which exhibit a high temperature viscosity susceptit bility are referredto as the non-parafllnic oilsn The heavy 01] fractions oifmany crude oils, from which lubricating oils are produced consist 2 of a mixture 'offhydrocarbons some of which exhibit a low temperature viscosit; susceptibility, some of which-exhibit an intermediate tempera;

ture viscosity susceptibility, and some of which exhibit a high' temperature viscosity suscepti bility. In order to" produce superior lubricating 1 on from hydrocarbon mixtures as described above, those oilspresent having ahigh viscosity temperature susceptibilityend those having an intermediate temperature viscosity susceptibility are separated from the oils present which exhibit a low temperature viscosity susceptibility. Solvent extraction is one oi the methods employed to separate the undesirable oilfifrom the desirable oil. Solvents, suchras'aniline,furfural; nitrobenzene, selenium oxychloride; sulphur dioxide or B B dichlorethyl etherare capable, un-

der the proper conditions of Qemperature and pressurejofdissolvingthe fractions presentwhich are non-paraflinic in cliaract'er. The foregoing solvents under proper'conditions of temperature andwpressure are capable of dissolving the oils present in the hydrocarbon mixture which exhibit 'ntermediateand" high temperature yiscos-' ity suscep ibilities. These oils' dissolved in the solvent may be separatedfromeach other by 45 coolingin which case the oils exhibiting the-in-.

termed ate temperature viscosity susceptibility are forced outofsolution.

These solventsform rela ively heavy solutions with the-non-parafflnic oil fractions and canbe senaratedfromthe insoluble parafilnic oiliractions by settlinn. The separated pareiilnicoil' fractions or raifinates and non-parafiinic oil fractions 01'' extracts-dissolved in solvent are then distilled to separate the solvent from the oil. 55 The parailinic iractions'may then be given such Los Angeles, Calii., assignors to Union Oil Companyof California,

corporation of California Application October 24, 1932, Serial No. 639,341

g i 12 Claims. (01.196 43) i This inventionhrelates to a process for the More specifically Los Angeles, CaliL, n

taining a relatively high concentration of nonparafllnic fractions whereas the'purifled oilis finally contacted with pure solvent. ner the maximum degree of refinement is usu- In this manally obtained because at the final stage of the extraction relatively pure oil is contacted withfresh solvent which has ahigh selective solvent power to separate the par'affinic and non-paraifinic fractions because it is not contaminated, with non-parafilnic oil. When continuous countercurrent extractlonis employed the extraction step may be carriedout in one stage wherein the solvent and oil flowtcountercurrently' or it may be carried out in a plurality of stages wherein the extracts obtained from the later stages of the process are returned to the earlier stages of the process and employed therein as the extracting medium. Thus in'the first extraction stage the oil to be extracted is contacted with solvent containing dissolved fractions from a la er stage.

The insolubleoil portion in theflrstst'age passes to the secondstage where it is contacted with solvent containing lessof the ex racted fractions; The insoluble oil from the second stage passes successively inthe same manner as described above,to the remaining extraction stages until it reaches the flnal'stage wherein itis extracted with pure solvent. In processes of this character the same temperature is employed throughout the system and as final products there are obta ned a fraction consisting largely of the non-parafllnic fractions ands. fraction which is in the main composed of theparaflinic fractionsv We have found it more des rable to carry out the extraction-of"hydrocarbonin xtures containing paramnic 'and non-parai'flnic fractions countercurrently in a plurality of stages maintained at d fferent temperatures and to separate from eachstage a rafilnate fraction. In such case the oil to be treated is contacted in the first stage at a relatively high temperature with solvent containing extracted fractions obtained from the second extraction stage in which the extraction has been carried out at a lower temperature than the extraction in the first stage. A raflinate and extract are separated in the first stage. The extract is passed through a cooler to lower the temperature upon which a further separation of oil and extract takes place. The cooled mass is then passed to a column where the extract settles out and is withdrawn. The insoluble oil in this column passes to a'second extraction stage where it meets solvent containing extracted fractions from the third extraction stage in which the extraction temperature is lower than that employed in the second stage. Further separation of rafilnate and extract is obtained in the second extraction stage and there is removed therefrom a second rafiinate and a. second extract. The extract from the second extraction stage is cooled in the same manner as the extract obtained from the first stage to obtain separation of an extract phase and a railinate phase. As has been explained above, the extract phase obtained at this point of the process constitutes the extracting medium employed in the first extraction stage. The rafiinate phase, herein, passes to the third extraction stage where it is treated in the same manner as described above, with a solvent recovered from 'a fourth stage operating at a lower temperature or in many cases three stages of extraction may be sufficient in which case the extraction in the third stage can be made with pure solvent. Thus we are able to obtain the maximum degree of separation of the parafilnic and non-parafiinic fractions and to conserve the quantity of solvent necessary to separate these fractions by our process.

It isa further object of our invention to separate the paraffinic fractions from the nonparaffinic fractions contained in hydrocarbon oils by extracting said oil in a plurality of stages with a solvent at successively lower temperatures in each stage. I

It is a further object of our invention to countercurrently extract a hydrocarbon mixture with a solvent into a plurality of fractions in which the oil in each successive stage is extracted at a different temperature than the extraction in the previous stage and to separate from each successive stage a raffinate fraction.

A further object of our invention is to countercurrently extract a hydrocarbon oil mixture in successive stages with a solvent, separate a ramnate and fractions dissolved in said solvent in each successive stage, cool the solvent and dissolved fractions and separate a fraction therefrom, pass the fraction separated from the cooled solvent to a later extraction stage for extraction with solvent and pass the solvent containing the remaining dissolved fractions to an earlier extraction stage to be employed therein as solvent.

The accompanying figure is a schematic arrangement of one form of apparatus which we may employ to carry out our process. Referring more particularly to the figure, oil from a source, not shown, and which may previously have been treated is introduced into the lower zone of column 2 through pipe along with an extracting medium introduced into the upper zone of the column through pipe 3. Owing to the difference in specific gravity of the extracting medium and oil these two liquids tend to separate. The extracting medium passes downward through the extracting column and during its passage dissolves certain of the non-paramnic fractions from the ascending column of oil. The oil from which the non-parafiinic fractions have been removed leaves the column through pipe 4 as a first rafllnate.

The temperature of the extraction in column 2 may be relatively high and in some cases we find it desirable to maintain this temperature a few degrees below the temperature of complete miscibility of the solvent and the oil. In some cases this temperature will be 10 degrees below the point of complete miscibility, in others it is desirable that we drop the temperature 40 below this point. v

The extracting medium and dissolved fractions are withdrawn from column 2 through line 5, valve 6 and line I to pump 8 which forces it through line 9 to cooler I0 where the temperature of the solution is lowered sufficiently to obtain a material separation of the oil dissolved in the extracting medium. The cooled mass in cooler i0 passes through line H to separator 12 where the solvent containing dissolved impurities settles out and is removed through line l3, valve l4 and line I5 to cooler l6 where it is cooled sufficiently to cause further separation of the dissolved fractions. This ma'ss then passes to mp9.- rator H where the solvent containing the remainder of the dissolved impurities settles out and is removed through line I8, valve l9 and line 20 to storage not shown. The insoluble oil in separator i2 rises to the top and passes to the lower zone of extracting column 25 along with the insoluble oil from separator H which may be withdrawn through line 2|, pump 22 and line 23 to extracting column 25. 'Extractlng medium enters the upper zone of column 25 through line 26 at approximately the same temperature as the oil entering the lower zone of column 25. As the extracting medium moves downward through the ascendingv column of oilit dissolves a portion of the non-paraflinic oil present. The insoluble oil is removed from column 25 through line 21 as a second raflinate. The solution of solvent and. dissolved fractions in column 25 is removed through line 28, valve 29 and line 30 to pump 3| which forces it through line 32 to cooler 33 where the temperature of the solution is lowered sufficiently to obtain a separation of the dissolved oil fractions from the solution of solvent and oil. The cooled mass then passes by means of line 35 to separator 36 where the solvent and remaining dissolved fractions settle out and are removed-through line 39, valve 40 4 and line 4| to pump 42 which forces it through line 43 into heater 44 where it is heated to approximately the same temperature as the oil entering column 2 through pipe I. From heater 44 this heated solvent which contains some dissolved non-parafiinic fractions passes by means of line 3 to the extracting column 2 as previously described. Due to its higher temperature and because it has been partially separated from its dissolved impurities in separator 36 its solvent power for the non-parafiinic fractions has been increased.

The insoluble oil in separator 36 rises to the top of the separator and passes by means of line 31 to the lower zone of column 38. Pure solvent is introduced into the upper zone of column 38 through line 46 from a source not shown and at a temperature. substantially the same as that of the cooled oil entering column 33 through line 31. The pure solvent passes downward through to colunlm I through the heater 4 and the heater in line In case cooler 51 and separator I are not in operation by reason of valve 48 being closed and valve 62 being open and it is desired to operate each stage at the same temperature then heater 6| functions merely as a flow line for the solvent and dissolved fractions passing from column 38 to column 25 and in case the temperature in column 25 is lowerthan the temperature in column 38 then heater 6| functions as a cooler for the solvent and dissolved fractions passing from the bottom of column 38 vialine 41, valve 62, line 65, line 60 and line 26 to column 25.

The foregoing example is merely illustrative of one method of carrying out our process and is not to be construed as limiting the invention which we claim.

We claim:

1. A process for the production of lubricating oil from a hydrocarbon oil mixture which comprises extracting said mixture with a solvent, separating a rafllnate and an extract dissolved in said solvent, cooling said solution of extract dissolved in said solvent to separate a parafllnic fraction from said solvent solution of extract, removing said paraillnic fraction from the remaining solvent solution of extract, continuously passing said cooled paraillnic fraction to a later extraction stage and extracting said fraction passed to said later extraction stage into a second raflinate and extract with a solvent.

2. A process for the production of lubricating oil from a hydrocarbon oil mixture which comprises extracting said mixture with a solvent into a rafflnate and an extract dissolved in said solvent, separating the rafllnate from the extract dissolved in said solvent, cooling said extract dissolved in said solvent to separate an insoluble fraction from the solvent and remaining dissolved fractions, removing said insoluble fraction from the solvent and remaining dissolved fractions, subsequently passing said fraction separated from said cooled extract to a later extrac-' tion stage and extracting said fraction passed to said later stage with a solvent into a plurality of fractions and passing said solvent and remaining dissolved fractions to an earlier extraction stage and extracting said 011 passing to said earlier extraction stage into a plurality of fractions with said solvent containing the remaining dissolved fractions.

3. A process for the production of lubricating oil from a hydrocarbon oil mixture which com prises separating a raiflnate and B B dichlorethyl ether containing dissolved fractions in an earlier extraction stage, cooling said B B dichlorethyl ether and dissolved fractions to separate an insoluble fraction therefrom, removing said in soluble fraction from said B B dichlorethyl ether and remaining dissolved fractions, subsequently passing said insoluble fraction to a later extraction stage and extracting said insoluble fraction passing to said later extraction stage with B B dichlorethyl ether.

4. A process for the production of lubricating oil from a hydrocarbon oil mixture which comprises separating a rafflnate and solvent containing dissolved fractions in an intermediate extraction stage, cooling said solvent containing dissolved fractions to separate an insoluble fraction from; the solvent and remaining dissolved fractions, removing said insoluble fraction from the solvent and remaining dissolved fractions, subsequently passing said insoluble fraction to a later extraction stage and extracting said fraction passed to said later extraction stage into a plurality of fractions with a solvent and passing said solvent containing the remaining dissolved fractions to an earlier extraction stage and extracting oil passing to said earlier extraction stage into a plurality of fractions with said solvent containing the remaining dissolved fractions.

5. A process for the production of lubricating oil from a hydrocarbon oil mixture which comprises separating a raillnate and B B dichlorethyl ether containing dissolved fractions from an intermidiate extraction stage, cooling said B B dichlorethyl ether and dissolved fractions to separate an insoluble fraction from the B B dichlorethyl ether and remaining dissolved fractions, removing said insoluble fraction from the B B dichlorethyl ether and remaining disolved fractions, subsequently passing said insoluble fraction to a later extraction stage and extracting said insoluble fraction passed to said later extraction stage with B B dichlorethyl ether, passing said B B dichlorethyl ether containing the remaining dissolved fractions to an earlier extraction stage and extracting oil passing to said earlier extraction stage with said B B dichlorethyl ether containing the remaining dissolved fractions.

6. A process according to claim 1 wherein the temperature of said last mentioned extraction of said parafllnic fraction recovered from the extract phase is lower than the temperature prevailing in said first mentioned extraction.

7. A process for separating a hydrocarbon mixture into a plurality of fractions which comprises commingling said oil with a selective solvent to separate a rafilnate insoluble in said solvent from extract phase comprising said solvent and oil soluble therein, removing said raffinate from said extract phase, cooling said extract phase to separate an insoluble fraction from the solvent and oil fractions remaining dissolved therein, removing said insoluble fraction from said solvent and oil fractions remaining dissolved therein, cooling said last mentioned solvent and oil fractions remaining dissolved therein to separate a further insoluble fraction and continuously extracting said last mentioned insoluble fraction with a selective solvent.

8. A process for separating a hydrocarbon mixture into a plurality of fractions which comprises commingling said oil with a selective solvent to separate a rafllnate insoluble in said solvent from extract phase comprising said solvent and oil soluble therein, removing said rafllnate from said extract phase, cooling said extract phase to separate an insoluble fraction from the solvent and oil fractions remaining dissolved therein, removing said insoluble fraction from said solvent and oil fractions remaining dissolved therein, cooling said last mentioned solvent and oil fractions remaining dissolved therein to separate a further insoluble fraction, commingling the insoluble fractions obtained by both said cooling steps and extracting said mixture with a selective solvent.

9. A process for the separation of paraiilnic from the non-parafllnic fractions of a hydrocarbon oil mixture which comprises extracting said oil with a solvent into a rafilnate and fractions dissolved in said solvent, separating said solvent containing dissolved fractions from said rafllnate, subsequently cooling said solvent containing dissolved fractions to separate an insoluble fraction from the solvent and remaining dissolved fractions, removing said solvent and remaining dissolved fractions from said insoluble fraction, thereafter passing said solvent and remaining dissolved fractions to an earlier extractionstage and extracting oil entering said earlier extraction stage into a plurality of fractions with said solvent and remaining dissolved fractions.

10. A process for the separation of paraflinic from the non-parafiinic fractions of a hydrocarbon oil mixture which comprises withdrawing solvent containing dissolved fractions from alater extraction stage, cooling said solvent containing dissolved fractions to separate an insoluble fraction therefrom, separating said solvent and remaining dissolved fractions from said insoluble fraction, subsequently passing said solvent containing remaining dissolved fractions to an earlier extraction stage andextracting oil passing to said earlier extraction stage into a plurality of fractions with said solvent containing remaining dissolved fractions.

11. -A process for the production of lubricating oil from a hydrocarbon oil fraction which comprises extracting said mixture with a solvent, sep arating a rafiinate and an extract dissolved in said solvent, cooling said solution of extract and solvent to separate a paramnic fraction from said cooled solution of extract, removing said insoluble paraflinic fraction from the remaining cooled solution of extract, subsequently passing said cooled solution of extract through a heater to raise the temperature of said solution and passing said heated solution of solvent and extract to an earlier extraction stage to be employed therein as the extracting medium.

12. A process for the separation of paraflinic and non-parafllnic fractions from an oil containing the same which comprises commingling said oil in an extraction stage with a selective solvent, forming a raflinate phase comprising relatively parafiinic oil fractions and an extract phase comprising selective solvent and relatively nonparaiiinic fractions, separating said phases, removing a parafiinic oil fraction from the extract phase, returning the selective solvent containing the remaining dissolved fractions to an earlier extraction stage, and extracting oil passing to said earlier extraction stage with the selective solvent containing the remaining dissolved fractions.

DAVID R. MERRILL. PHILIP SUBKOW. 

